This section is intended to introduce various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion should be helpful in providing background information to facilitate a better understanding of the various aspects of the present disclosure. These statements are to be read in this light, and not as admissions of prior art.
An engine for aircraft propulsion requires intake air that is free from contaminants to provide for efficient combustion and avoid damage to internal engine components. Some known compressors and turbines are designed with small clearances between moving parts that maximize efficiency, but which also increase vulnerability to damage of engine parts from small foreign particles. Contamination of intake air, even in a small amount, may cause premature wear on engine components, increases maintenance costs, and degrades operational performance and reliability. Aircraft are exposed to contaminants when operating at low altitudes where air is frequently contaminated with material from the ground, such as sand and dust. This problem may be aggravated for helicopters due to rotor downwash and prolonged low-altitude operation. Systems which remove foreign particles from intake flow have been developed to protect the engine from damage. For example, a filter may be positioned across the intake of the engine.
Filtered intake systems typically have a bypass door which provides an alternate entryway for air. During normal operations, the door remains closed and sealed to the alternate entryway to prevent contaminants from leaking into the filtered air stream. But if the contaminant separator becomes partially or fully restricted, the bypass door is opened to permit greater intake of air and safe operation of the engine.